The present invention relates to printing apparatus and paper feeding apparatus therefor, and more particularly to a paper feeding apparatus which will automatically feed individual sheets of paper to a printing device, and properly align and position the paper for the start of printing thereon by the printing device.
Tremendous advances have been made in the last few years in automating office procedures. Conventional typewriters have grown into mini-computers performing word processing, storage and other functions. The speed at which these machines produce words on paper is increasing at a rapid rate.
As added speed and sophistication are developed into such machinery, the actual putting of words onto paper becomes auxilliary to the main function of collecting and organizing the information into a format to be printed. In order to have flexibility and speed, many systems have been developed where an operator manipulates words on a cathode ray tube or other word processing equipment until the final copy is in the format desired. With all of these advances, it has developed that today one of the major bottlenecks in terms of time, and therefore usefulness of this equipment, is the rate at which paper can be brought to and moved past a printing head to produce the final hard copy.
Of course it is possible to use continuous sheets of perforated paper, as is commonly done in computer applications, having sprocket holes along the side thereof to continuously feed and move the paper through an impact printer. This however requires special paper which is not suited to the many requirements for which normal typewriting is employed.
Many machines exist, both copying machines and printing machines, which automatically feed paper past a printing or reproducing station. These machines are normally run synchronously such that prior to the time that paper is fed, the information to be imparted to the paper is already organized and the paper is moved past the printing head in a continuous fashion. This is not suitable for impact printing devices since impact printing is accomplished with the paper stationary rather than moving, and further the adaptation of normal typewriting type printing requires the moving of paper not only on an intermittant basis but also in the forward and reverse direction in accordance with the information to be typed. Still further, with such existing equipment, it is generally not possible to manually feed separate sheets of paper, which may be of a different size or thickness (such as for example envelopes), without disconnecting the equipment from the printing apparatus.
It is of course possible to radically change the printing equipment to conform with the needs of high-speed paper feeding. However, it is an object of this invention to provide a paper feeding apparatus to conform with the requirements of existing impact printing equipment rather than requiring the radical modification thereof. In particular, it is an object to provide a paper feeding apparatus which is capable of being retrofitted with respect to existing printing devices (i.e., distributed as an after market product) as well as being capable of being sold and distributed with or as an integral part of the printing apparatus.